Cartridge magazine with spring guide means



J1me 1957 G. w. PATCHETT CARTRIDGE MAGAZINE WITH SPRING GUIDE MEANSFiled April 21, 1953' wwlvenior h' {9am Attorneys pressing the spring 0.

CARTREDGE MAGAZINE WITH SPRING GUIDE MEANS George William Pratchett,Gidea Park, England Application April 21, 1953, Serial No. 350,081

4 Claims. (Cl. 42-50) This invention relates to cartridge magazines forautomatic firearms of the kind having curvilinear side walls united bycurved front and back plates to form a box magazine the sides of whichtaper slightly towards each other in conformity with the contours of thecartridges to be accommodated in the magazine.

The object of the present invention is to provide an improved andsimplified form of cartridge magazine of the kind above describeddesigned to facilitate charging cartridges into a magazine as well a tomaintain an uninterrupted feed during operation by ensuring againstjamming due to buckling of the spring which is compressed as themagazine is charged.

According to the invention a cartridge magazine of the kind describedfor an automatic firearms is characterised by the employment of ahelical compression spring maintained in arcuate form lengthwise tocorrespond with the contours of the magaizne by guide elements disposedalong the side walls of the magazine.

According to a preferred form of the invention a cartridge magazine ofthe kind described is formed or provided with internal rails, ribs orthe like arranged to maintain a helical compression spring in arcuateform lengthwise to correspond with the contours of the magazine and alsoto constitute guide rails upon which the cartridges can roll towards thebreech as the spring expands during the operation of the firearm.

Reference will now be made to the accompanying drawings in which:

Fig. 1 is a longitudinal sectional elevation of a cartridge magazineconstructed according to the invention, and

Fig. 2 is a cross-sectional view taken on the line IIII of Fig. 1.

In the construction illustrated, a indicates a cartridge magazine ofknown arcuate form into which cartridges are adapted to be charged atthe end b gradually com- In arrangements of this character hithertoemployed it has been common to form the magazine of substantiallyrectilineal cross-section and to employ a coiled spring whose individualcoils are of similar form. This arrangement possesses the disadvantagethat the spring is liable to become deformed under compression wherebythe coils may interlock and the cartridge feed become jammed. Accordingto the present invention the spring 1: is of the helical compressiontype and is retained lengthwise in arcuate form to correspond with thelongitudinal shape of the magazine, To this end the magazine is formedby pressing from sheet metal to an isosceles trapezium cross sectionalshape as shown in Fig. 2. In

aired States Patent 9 ice addition the sides of the magazine are formedeach with two internal ribs or rails d which extend throughout thelength of the magazine and in conformity with the arcuate curvaturethereof as shown in Fig. l. The spring 0 is disposed between theserails, as shown in Fig. 2, which prevents displacement of the spring orany of its individual coils from the arcuate form thereby preventing anytendency of the spring to become partially displaced under compressioninto the upper or lower parts e and f of the cavity within the magazineeven when under extreme compression caused by the full charge ofcartridges. As the operation of the firearm proceeds the cartridge arefed one by one into the breech by the expansion of the spring whichthroughout its expansion i maintained by the rails d concentric with anarcuate axis parallel to the top and base of the magazine. Also, therails d facilitate the feed as they afford guides upon which thecartridges can roll freely towards the breech.

Although the invention has been particularly described with reference toguide rails a pressed out of the walls of the magazine it is to beunderstood that they could be formed in other ways, for example, bywelding onto the inner surfaces of the magazine side walls.

I claim:

1. A cartridge magazine for an automatic firearm comprising a casinghaving longitudinally curvilinear side Walls united by curved front andback plates to form a box magazine whose sides taper towards each otherto conform to the contours of the cartridges, a helical compressionspring extending in arcuate form lengthwise of the magazine, and ribs oflongitudinally arcuate form projecting inwardly from the side walls ofthe magazine in transversely spaced relation and engageable with thespring to hold it against transverse movement in the magazine.

2. A cartridge magazine according to claim 1 wherein said ribsprojecting from said side Walls are located thereon between and spacedtransversely from said front and back plates and form guide rails uponwhich the cartridges can roll towards the breech of the firearm as thespring expands during the operation of the firearm.

3. A cartridge magazine for an automatic firearm comprising a boxmagazine-curved in the direction of its length and formed of isosceletrapezium cross-section, a helical compression spring arcuately curvedlongitudinally and expansible lengthwise of the magazine, andlongitudinally arcuate ribs projecting inwardly from and spacedtransversely of the internal surfaces of the side walls and engageableby peripherally spaced portions of the opposite sides of the helicalspring to retain the spring in arcuate form in the direction of itslength and to form guide rails for the cartridges.

4. A cartridge magazine as defined in claim 3, wherein said ribs are inpairs on the respective side walls of the magazine, the ribs of eachpair being spaced apart transversely of the magazine a distance toreceive between them arcuate portions of the coils of the spring at therespective side thereof.

References Cited in the file of this patent UNITED STATES PATENTS2,396,816 Boudreau Mar. 19, 1946 2,441,735 Warner May 18, 1948 2,510,831Patchett June 6, 1950

